All-fiber curvature sensor based on helical four-core fiber

Abstract An all-fiber Mach–Zehnder interferometer curvature sensor based on a helical four-core fiber (HFCF) is proposed. The sensor is constructed by splicing two sections of single-mode fiber with a short section of HFCF. A simulation model of the HFCF is established using the beam propagation method, and the consistency between experimental and simulation results is verified. Experiments show that the proposed sensor exhibits a curvature sensitivity of 4.1545 nm m −1 within the curvature range of 0.8–188 m −1 °C –1 within the temperature range of 25 °C–90 °C. Furthermore, the sensor has a simple structure and low manufacturing cost. The use of helical core fiber offers a novel and feasible solution for designing fiber curvature sensors.